for combo point builders use ambush if you can (stealth or shadowdance), use hemo to keep glyph of hemo up, else use backstab. If you can't get behind then hemo, but you're losing a lot of dps to do so.

So outside of shadowdanced/pull you basically backstab for cp (with a hemo every 24 secondsish), and then depending on your gear you keep snd and recup up with evis in between. My rogue's got pretty crappy gear and generally goes snd -> evis -> recup -> evis -> snd -> evis -> recup -> evis etc, but with better gear you can squeeze in a second evis more frequently. Because you're dependent on being in a raid for a lot of your resource generation (10% melee haste and combo points from HaT) practicing on a dummy solo is very different from being in a raid, so you really need to either grab a friend or hit morchok a few times in lfr to get a good feel for it.

The thing with sub though is that it has a lot of subtleties (hurrrrrrrr) to optimise dps, for example I didn't touch shadowdance, which is a large part of your damage. The EJ thread does a good job to cover most of them and they will make sense once you've got a feel for the basic rhythm of the rotation. The macros there are also pretty nice for simplifying how many buttons you have to press - honestly, setting up your bars properly is the most difficult thing about starting to play sub. Also learning to be patient and wait for HaT to give you your last combo point takes a bit of doing if you're coming from spam-happy combat.

Yeah, you want to pool energy prior to shadowdance or vanishing so you can get as many attacks off during shadowdance/find weakness uptime. Outside of that there's no rush, and by pooling you'll find it easier not to waste HaT cp.

Do your healers not let you stay in for black phase? There's no reason sub shouldn't shine on Morchok, it's #1 spec on wol for 25 heroic for a reason. Combat's top on 10 man because some guilds have managed to tank them together and blade flurry.